1. Field of the Invention
The present invention relates to a seat structure, to be in more detail, a seat structure suitably used for a seat of a transportation equipment such as a plain, train, ship, fork lift and automobile.
2. Description of the Relevant Art
A vehicle seat which uses a three-dimensional net member (solid knitted fabric) as a cushioning layer is disclosed, for instance, in a patent document 1 (Japanese Patent Laid-open No. 2002-177099). Namely, the three-dimensional net members are strained on a back frame and a cushion frame forming a seat back and a seat cushion respectively
Since the vehicle seat disclosed in the patent document 1 uses a three-dimensional net member, it has sufficient cushionability though it is thin, and is excellent in air permeability. However, in the vehicle seat disclosed in the patent document 1, a seat cushion is provided with a vibration absorbing function by arranging a flat-type supporting member supported by a coil spring on a bottom portion of the three-dimensional net member, but a vibration absorption measure on the seat back side is not regarded as important so much. Further, since the three-dimensional net member provided on the seat back is strained at a low tension, it sometimes makes an impression to have a slight slack in the vicinity corresponding to the waist portion of a seated person, which makes a problem in appearance. Further, since it is structured that the three-dimensional net member is strained on the back frame and the cushion frame like a hammock, it often gives a feeling of receiving a lateral pressure on a side portion of the body or a feeling of forward slippage of the haunches when seated.